1. What is Blockchain?
A) A type of cryptocurrency
B) A decentralized digital ledger
C) A centralized banking system
D) A cloud storage service
Answer: B) A decentralized digital ledger
2. What is the primary purpose of a blockchain?
A) To store and manage financial transactions
B) To maintain a distributed and tamper-proof record of data
C) To replace traditional databases
D) To increase internet speed
Answer: B) To maintain a distributed and tamper-proof record of data
3. Which of the following is NOT a characteristic of blockchain?
A) Decentralization
B) Immutability
C) Central authority control
D) Transparency
Answer: C) Central authority control
4. What is the first blockchain-based cryptocurrency?
A) Ethereum
B) Ripple
C) Bitcoin
D) Litecoin
Answer: C) Bitcoin
5. Who is credited with inventing Bitcoin and blockchain technology?
A) Vitalik Buterin
B) Satoshi Nakamoto
C) Elon Musk
D) Charles Hoskinson
Answer: B) Satoshi Nakamoto
6. What type of cryptographic function is used in blockchain for security?
A) Symmetric encryption
B) Hash functions
C) Public and private key encryption
D) Both B and C
Answer: D) Both B and C
7. Which consensus mechanism does Bitcoin use?
A) Proof of Stake (PoS)
B) Proof of Work (PoW)
C) Delegated Proof of Stake (DPoS)
D) Byzantine Fault Tolerance (BFT)
Answer: B) Proof of Work (PoW)
8. What is the role of miners in a blockchain network?
A) To create smart contracts
B) To validate and add transactions to the blockchain
C) To regulate transaction fees
D) To act as intermediaries in transactions
Answer: B) To validate and add transactions to the blockchain
9. Which of the following blockchains supports smart contracts?
A) Bitcoin
B) Ethereum
C) Litecoin
D) Dogecoin
Answer: B) Ethereum
10. What is a smart contract?
A) A physical contract stored on the blockchain
B) A self-executing contract with pre-defined conditions
C) A document signed by multiple parties
D) A government-issued digital agreement
Answer: B) A self-executing contract with pre-defined conditions
11. What does a hash function do in blockchain?
A) Encrypts transactions
B) Converts an input into a fixed-length string
C) Creates public and private keys
D) Tracks transaction history
Answer: B) Converts an input into a fixed-length string
12. What is a fork in blockchain technology?
A) A hardware upgrade
B) A change in the protocol rules
C) A security breach
D) A transaction failure
Answer: B) A change in the protocol rules
13. What is the main advantage of blockchain over traditional databases?
A) Centralized control
B) Faster data retrieval
C) Enhanced security and transparency
D) Unlimited scalability
Answer: C) Enhanced security and transparency
14. Which type of blockchain is open to the public and allows anyone to participate?
A) Private blockchain
B) Consortium blockchain
C) Public blockchain
D) Hybrid blockchain
Answer: C) Public blockchain
15. What is gas in the Ethereum blockchain?
A) A measure of computational work required for transactions
B) The fuel used for mining
C) A cryptocurrency token
D) A security protocol
Answer: A) A measure of computational work required for transactions
16. Which of the following is NOT a real-world application of blockchain?
A) Supply chain management
B) Voting systems
C) Cloud computing
D) Healthcare records
Answer: C) Cloud computing
17. Which of the following is NOT a blockchain consensus mechanism?
A) Proof of Work (PoW)
B) Proof of Stake (PoS)
C) Proof of Transaction (PoT)
D) Delegated Proof of Stake (DPoS)
Answer: C) Proof of Transaction (PoT)
18. What is the primary function of a node in a blockchain network?
A) To store a copy of the blockchain and validate transactions
B) To act as a central server for transactions
C) To provide internet connectivity
D) To generate private keys
Answer: A) To store a copy of the blockchain and validate transactions
19. Which blockchain technology allows interoperability between different blockchains?
A) Bitcoin
B) Ethereum
C) Polkadot
D) Litecoin
Answer: C) Polkadot
20. What is the term used when a blockchain is split into two separate chains due to disagreements in protocol updates?
A) Merge
B) Split-chain
C) Fork
D) Breakdown
Answer: C) Fork
21. Which layer of blockchain handles data transmission between nodes?
A) Application layer
B) Consensus layer
C) Network layer
D) Data layer
Answer: C) Network layer
22. Which of these is a potential drawback of blockchain?
A) High energy consumption in PoW
B) Slow transaction speeds in some blockchains
C) Scalability challenges
D) All of the above
Answer: D) All of the above
23. What is the main function of a blockchain wallet?
A) To store blockchain transactions
B) To store private and public keys for cryptocurrency transactions
C) To mine new coins
D) To validate blockchain transactions
Answer: B) To store private and public keys for cryptocurrency transactions
24. What is the Lightning Network used for?
A) Improving Bitcoin's scalability
B) Enhancing Ethereum smart contracts
C) Mining new cryptocurrencies
D) Encrypting blockchain transactions
Answer: A) Improving Bitcoin's scalability
25. Which organization developed the Hyperledger blockchain framework?
A) Microsoft
B) Linux Foundation
C) Ethereum Foundation
D) Google
Answer: B) Linux Foundation